﻿378 M. G. Quincke on the Capillary Phenomena 



If the tube is not perfectly cylindrical, then r is the radius of 

 the tube at the place where the capillary meniscus of the com- 

 mon surface meets the sides of the capillary tube. 



In the case in which g> 12 > 90°, this mean elevation h i2 may 

 even be negative ; there will then be a depression. For the case 

 in which the angle is known (for example when &> 12 =0 or 180°), 

 the capillary constant a 12 of the common surface of both liquids 

 can be calculated from equation (15). 



16. The experiments on water and oil of turpentine were 

 made thus : into a glass cylinder 40 millims. in diameter and 250 

 millims. in height some water was poured as liquid 1, and upon 

 this oil of turpentine was very carefully allowed to trickle down 

 the side of the glass cylinder as liquid 2. As an elevation of the 

 capillary meniscus was to be expected, the height chosen for the 

 column of oil of turpentine was considerably greater than that of 

 the layer of water. 



By means of the blowpipe-lamp, glass threads of suitable thick- 

 ness were made from thicker glass tubing purified as much as 

 possible. In a capillary tube so prepared, open at both ends, I 

 allowed a column of water to rise and then closed the upper end 

 by melting it, so that the tube was nearly filled with water. The 

 glass thread was passed through two caoutchouc rings and thus 

 fastened to a strip of pure plate glass 300 millims. long and 10 

 millims. broad, which had a scale of millimetres engraved upon it. 

 Towards the upper end of the glass thread and beneath the upper 

 end of the column of water a mark was made with a file ; the 

 strip of plate glass and capillary tube were immersed in the glass 

 cylinder, so that the file-mark was in the oil of turpentine and 

 the lower end of the glass thread stood in the water. When the 

 point of the glass thread was broken off at the file-mark under 

 oil of turpentine, the water in the capillary tube sank, the oil 

 of turpentine pressed upon it, and the meniscus concave above 

 sank to a height h l<2 above the horizontal limiting layer of water 

 and oil of turpentine, which was read off on the vertical milli- 

 metre-scale by a horizontal telescope. The glass tube was cut 

 in the place where the capillary meniscus was found, and the 

 inner diameter 2r of the section measured with microscope and 

 ocular micrometer in the manner described in § 4. 



Experiments Nos. 1 and 2 of Table XIV. were made in the 

 manner described ; No. 3 differed in the capillary tube being 

 filled with oil of turpentine instead of water, with the upper end 

 in oil of turpentine and the lower end immersed in water. When 

 the upper end was broken off under oil of turpentine, the water 

 rose in the capillary tube, which was moistened inside with oil of 

 turpentine. Thus in the restoration of equilibrium the meniscus 

 moved upwards in No. 3 in a capillary tube moistened with oil of 



